1. Field of the Invention
The present invention related to the field of optical equipment, and more particularly to a novel marking machine or apparatus for locating precise areas on a progressive optical lens and for marking the optical lens so that correct prescription of the lens can be read with a lensometer.
2. Brief Description of the Prior Art
It is a conventional practice to refer to glass or plastic optical lenses held in a frame as "eyeglasses" and for these eyeglasses to be worn on ones face to correct vision deficiencies or shade the eyes from sunlight or other bright sources. It is not uncommon for the owner of eyeglasses to buy a replacement or "pair" of eyeglasses. Such owner's usually do not remember their eyeglasses prescription and therefore have no way of conveying this information to an optical store or laboratory. Accordingly, each optical store or laboratory must be prepared to determine the prescription from the eyeglasses themselves. Eventually, a machine referred to as a "lensometer" is used in optical stores to determine the prescription. The eyeglasses are placed in the lensometer and the necessary parameters, such as the number of diopters, focal length and power are read from the machine.
While a common form of eyeglasses is the bifocal eyeglass, a newer type of eyeglass is known as the "progressive" bifocal. This type employs two lenses, one for distance, and one for close work. However, there is no visual line of separation between the lenses and they are blended together over a short distance, hence the term "progressive". Because there is no observable line of division between lenses, use of the lensometer is restricted to certain areas of the lenses where the true prescriptions, as opposed to the transitional area prescription, may be viewed and the parameters determined. In order to locate the place on the lens where these prescriptions can be accurately read, manufacturers of progressive lens have created an international standard. This standard is based upon a horizontal "line" that is determinable from observation of two symbols such as small circles or squares, set in spaced-apart arrangement on the lens that are very lightly laser engraved on the lens so that the "reference" line may be hypothetically drawn between them. Each manufacturer of "progressive" lens then sets its area for lensometer viewing in a small circle, usually above and below the "reference" line. Once the correct area for obtaining the prescription of the "progressive" lens has been determined, marking is made to specifically indicate the correct location.
Coventional lens marking apparatuses have no means for magnifying the reference numerals or indicia during the locating procedure and it is difficult to visually observe the procedure since the work is close and no illumination means is provided other than ambient light. Also, conventional means for actually marking the lens is crude, cumbersome and awkward for an optician to use. Furthermore, conventional lens marking machines are generally intended to be placed on a flat surface and do not provide a means for articulation so as to accommodate for sloping surfaces on which the machine may rest.
One attempt to provide a suitable lens marker is described in co-pending and co-owner patent application having Ser. No. 08-550,598.
Therefore, a long standing need has existed to provide a novel lens marking machine for locating the exact spots on "progressive" optical lens so that the resultant marking can indicate the correct prescription of the lens which may be subsequently read with a lensometer. Such a means should include magnification of the referenced information as well as illumination means for assisting the viewer in viewing the entire procedure.